Casing of chemical diffuser



FIG. 1 is a perspective view of a casing of chemical diffuser showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof, the left side view being a mirror image thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is reference view showing the condition in use thereof.

The portions of the article in broken lines are shown for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a casing of chemical diffuser, as shown and described. 